A conventional inspection apparatus includes, e.g., a mounting table for mounting thereon a target object (e.g., a wafer) to be inspected, the mounting table having therein a temperature controller for controlling the temperature of the wafer, a vertical drive mechanism for moving the mounting table up and down, an XY table for moving the mounting table and the vertical drive mechanism in X and Y directions, a probe card arranged above the mounting table, and an alignment mechanism for accurately aligning a plurality of probes of the probe card with a plurality of electrode pads of the target object placed on the mounting table. The temperature of the wafer placed on the mounting table is controlled to a predetermined value by the temperature controller. A specified device formed on the wafer is brought into electrical contact with the probes of the probe card through the alignment mechanism. Then, the probe card is overdriven by a prescribed overdrive amount so that the electric characteristics of the device can be inspected under a predetermined contact load.
In some cases, the inspection apparatus performs a high temperature inspection by heating the wafer to a high temperature of, e.g., 100° C. or more. In other cases, the inspection apparatus carries out a low temperature inspection by cooling the wafer to a temperature of, e.g., minus several tens of degrees centigrade. When performing the high temperature inspection or the low temperature inspection, the target object is heated or cooled to a predetermined inspection temperature by the temperature controller provided in the mounting table. While controlling the position of the mounting table with the vertical drive mechanism, the device and the probes are brought into contact with each other under a specified contact load. The high temperature inspection or the low temperature inspection is performed in this state. The vertical drive mechanism includes, e.g., a ball screw connected to the mounting table and a stepping motor for rotating the ball screw. The stepping motor controls the amount of rotation of the ball screw and, eventually, controls the vertical position of the mounting table with increased accuracy.
In case of performing, e.g., the high temperature inspection of the wafer, the wafer placed on the mounting table is heated to, e.g., 100° C. or more, by use of the temperature controller provided in the mounting table. The wafer placed on the mounting table is aligned with the probes of the probe card by means of the alignment mechanism. In a state that the wafer and the probes are in contact with each other under the predetermined contact load, the electric characteristics of the wafer are inspected at a high temperature of 100° C. or more.
In an initial stage of the inspection, however, the probe card is not yet heated while the wafer is already heated to a temperature of 100° C. or more by the temperature controller. Thus, there exists a great temperature difference between the wafer and the probe card. For this reason, if the wafer is overdriven by a predetermined amount to bring the probes into contact with a first device of the wafer when inspecting the latter, the probe card is heated and gradually expanded by the heat radiated from the wafer during the contact. Therefore, the device and the probes make contact with each other under a load greater than the predetermined contact load, which may possibly cause damage to the device or the probes.
In view of this, the high temperature inspection is performed after preheating and completely heat-expanding the probe card. As the probe card becomes greater in size, however, it takes a long time, e.g., 20 to 30 minutes, to preheat the probe card. For example, Japanese Patent Laid-open Publication No. 2007-088203 (JP2007-088203A) discloses a technique of shortening a preheating time of the probe card by making the probes of the probe card brought into direct contact with a wafer heated to a predetermined temperature and preheating the probe card near the wafer.
In the technique disclosed in JP2007-088203A, however, a preheating time is still required in addition to an actual inspection time. Therefore, there is a limit in shortening the total inspection time. Furthermore, if the wafer is moved away from the probe card during index movement of a target object, the probe card is cooled to thereby change the height of the tips of the probes. For this reason, the contact load is changed each time when the index movement is carried out. In this case, however, it is impossible to control the contact load. Meanwhile, when performing a low temperature inspection of the wafer, there is a need to cool the probe card to a temperature near the wafer temperature.